To reverse a string

There are multiple ways to implement a string in reverse order, and the following three methods are all manipulated on the original string.

Way one. Operations using arrays

1 Char*REVERSESTR (Char*str)2 {3     Char*temp =str;4     intIndexleft =0;5     intIndexright =0;6     if(str = =NULL)7     {8         returnNULL;9     }Ten      while(*temp! =' /') One     { Aindexright++; -temp++; -     } the     //point to the last character ' \ s ' of the previous -Indexright = Indexright-1; -      -      while(Indexright >indexleft) +     { -         Chartemp =Str[indexleft]; +str[indexleft++] =Str[indexright]; Astr[indexright--] =temp; at     } -  -     returnstr; -      -}

Way two. Manipulate with pointers

Char*REVERSESTR (Char*str) {    Char*left =str; Char*right =str; if(str = =NULL) {        returnNULL; }     while(*right! =' /') { Right++; } Right--;  while(Right >Left ) {        Chartemp = *Right ; *right++ = *Left ; *left++ =temp; }    returnstr;}

Mode three. Do not use the third variable

1 Char*REVERSESTR1 (Char*str)2 {3     Char*left =str;4     Char*right =str;5     if(str = =NULL)6     {7         returnNULL;8     }9      while(*right! =' /')Ten     { Oneright++; A     } -right--; -     /*characteristics of using XOR operation a = a^b^b B = A^b^a*/ the      while(Right >Left ) -     { -*left = *left ^ *Right ; -*right = *left ^ *Right ; +*left = *left ^ *Right ; -left++; +right--; A     } at     returnstr; -}

To reverse a string